The set theme was "relay".
We have read before about evolution and about what one man calls "the selfish gene" - the bizarre process by which characteristics are transferred and retained over countless millenia, though their original owners are long since dead. The relayance of characteristics, from one generation onto the next, has long been known in any case.
"He has your eyes"
"Her mother's bearing"
"We will breed from this rose, it has a most vibrant hue".
Sometimes the baton is dropped, and usually that's a disaster. Race over. Team Mutant DNF.
On the other hand the genetic fumbles can produce, on rare freak occasions, advantages slight and great. Sometimes obvious - a gene directing iron compounds to the teeth of beavers, for example, giving them a ferrous constitution to match their chisel shape. Sometimes they are just fortuitous and perverse - think of a mutation to stunt the growth of poppies, at a time when tall ones are being cut.
The results are copious and spectacular. Whole worlds of bizarre monsters have died out in the distant past, more than one of them, before we even have to think about what might come in future. Presumably whole worlds of monsters are out there now, in the Milky Way and beyond.
What the word 'evolution' brings to my mind, though, is a witless creature, an ancient mudfish. Capable physically of existing on land for long enough to take advantage of the juicy vegetation growing there (which itself has never had need of thorns, tough barks or sharp tastes; never having had to protect itself from mouths); but not yet behaviourally evolved to make the most of its accidental lungs, being as neither its own unwitting parents nor any of their forebears had ever had the capability, never mind the need, of gasping on the land.
So it and some of its mutant brothers and sisters flop pioneeringly about at the water's edge, fields of naked green abundance all about them, accidentally taking a giant leap for the entire animal kingdom of earth and accidentally chewing the luscious land plants. Probably they get sunburnt quite regularly before the tide comes in again.
Brough to maturity it mates and more fish like it - put together wrongly in such a way that these humble faulty fish are miraculously given access to an entire virgin Eden - are made.
Those fish begat, and their offspring begat, and so on, and eventually it was them that gave rise to the entire history of animals on the land on this planet, including me, reading you this story, and you, listening to me read it.
This fish really existed; it must have. We know it must have. And it can't have known what it was doing. Of course it can't. It can't have pictured cities or cheetahs or antelope or seen its descendants the Bear pawing its contemporaries' descendants the Salmon out of the surging river. It can't have foreseen dinosaurs or birds or the bow and arrow. But I'd like to think, nevertheless, a moment of revelation of sorts for that fish, a dim revelation of whatever primitive kind it was capable of at the limits of its consciousness, perhaps just at the moment when, panicking about getting back to the water, as it must have done, and not quite managing it, and then finding that in fact it was persisting in that dangerous environment along the water's edge where its less capable relatives' bones were strewn; I'd like to think that maybe it at least took a moment to think, before it spawned the future of life on our planet as we know it - that maybe at least a sensation along the lines of "gosh" might have occurred to it in its fishy way. "Gosh. This is different."